1. Field of the Invention
This invention relates to lubricating compositions and more particularly lubricants having enhanced antiwear/extreme pressure and/or anti-oxidant capabilities.
2. Description of the Prior Art
Over the years, the development of satisfactory lubricating oil and grease compositions for use under extreme pressure, high temperature and high speed conditions has received widespread attention Consequently, numerous additives have been proposed to enhance the physical and chemical properties of these compositions when intended for such service. Such additives are compounds that generally contain lead, sulfur, phosphorus, halogen (principally chlorine), and carboxylate salts, organic phosphates and phosphites. The list also includes chlorinated waxes, sulfurized unsaturated organic compounds, heavy metal sulfides such as lead sulfide and molybdenum disulfide, zinc dithiophosphate and antimony thioantimonate.
These additives, although effective under extreme pressure and high temperature conditions, have certain disadvantages. For example, environmental concerns make lead-containing additives undesirable. Antimony thioantimonate, another widely accepted additive for producing extreme pressure lubricants and greases, is expensive, thus significantly increasing the manufacturing costs of said lubricants. Because of its toxicity, disposal is also costly. There is therefore a need for lubricating additives which are environmentally benign and inexpensive to use. The present invention provides such an additive.